Volvo EC Series Cab Heaters

[Muz]

Cab heater failures at this time of year are not uncommon. The reasons for failure can be many and varied, worn brushes are common, and other problems associated with dirt ingress, as they tend to be mounted in places like under the operators seat. As usual the manufacturer will source the cheapest possible kit and fit it, then charge a small fortune when you need to replace it.

It must be said, that some manufacturers will now sell you a 'half shell' which is the motor unit only, since, often its just that thats failed, and why would you need to buy a heat exchanger as well ? ... it all depends on the dealer, but be sure ... it will cost the usual small fortune to buy it, what ever you need.

Here I'm going to walk you through a failure of one a had a while ago, and its been sat on the bench for a while until I turned my attention to it. The fault ? ... it was blowing fuses .. removal identified that the motor was turning, but very stiffly, so the unit was drawing a lot of current and melting fuses.

Time to open up the case.

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It comes in two halves ... just pop the clips apart to open it up ... looks like my apprentice has had a go at this one and busted some clips

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So here its open and we can see the heater matrix and the style of fan ... the three wires are the earth and two +12V lines coming from the switch in the cab .. giving a fast, and medium speed for the motor .. or as the operator would know it .. a wee bit warm, and roastin' The motor has a built in resistor or shunt, which is why both feeds are 12V and keeps things simple at the cab electrics end.

Inspection of the motor revealed that part of the bearing on one side (which is a small brass bush) was siezed on the motor shaft and rotating in the bush clamp .. this was what was causing the drag.. essentially the shaft had rusted and expanded, and bound on its simple bearing

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So .. off with the impellor and strip the bearing out
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Now remove small roll pin A that locates in the impellor , circlip B and the bush locater clip .... this will let you get access to the brass bearing 'C' Just watch .. that under the circlip is a small shim .. watch you dont lose it
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The bush locator pings off each side, and actually found this a bit tricky to snap back in when re assembling because theres an elecrical block inside the motor case hard against the clip internally on one side
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Just use pliers to winkle off the brass bush, polish up the shaft with some fine emery paper and oil, then reassemble in reverse order

I damaged the original fastener when I removed it so I fitted a new one on reassembly

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Then clipped the case back together and ran and tested

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There you go Many fitters would have chucked that in the bin ... but it was easily fixed for about 3/4rs of an hours work and the princely sum of one fastener .. another couple of hundred in your pocket and not the dealers !

[jackpreacher]

Excellent run down of the job Muz, thanks for taking the time.

My EC15 blower is fine, but no heat. It's not that I've looked into it as it should be just a heat exchanger core blockage or similar, but with the UK weather getting cold right now......brrr.....

[Muz]

Could be a couple of things .. theres a valve down by the RHS console inside the cab opens and shuts the flow to the heater .. but you cant easily see it make sure its fully open .. or one of the hoses has got 'pinched' if someone has removed the cab. or blocked them off as they are a pain in the ass .. Ive modified mine on some machines withh connectors to allow cab removal

[jackpreacher]

EC15B no heat in cab

The hot and return pipes to the cab heater are the two pipes than run out past the oil cooler ? One is hotter than the other but no heat in the cab. I assume there is no pinching because of the temperature differential in the pipes. The control dial is set to full (clockwise).

I will investigate further in the morning.

A good fix though Muz, nice to see the innards.

[jackpreacher]

I had quick look over my EC15's heater circuit today as last night was -8C and the whole machine was covered in ice. Actually, on start up 'Doug' revved up so I shut him down only to discover the ignition key in the 'off' position didn't release the 12V energising the solenoid so, as the engine was trying to stop, the starter kept going. It sorted itself out after a few MP administrations to the ignition housing

Anyway, no heat today. I'll check it further in the morning.

[jackpreacher]

MP

Mechanical Persuasion

[Muz]

I had quick look over my EC15's heater circuit today as last night was -8C and the whole machine was covered in ice. Actually, on start up 'Doug' revved up so I shut him down only to discover the ignition key in the 'off' position didn't release the 12V energising the solenoid so, as the engine was trying to stop, the starter kept going. It sorted itself out after a few MP administrations to the ignition housing

Anyway, no heat today. I'll check it further in the morning.

Thats the reason I removed a starter last week, but my conclusion was that the start relay had jammed on, keeping it engaged, as the starter was fine, as was the key switch.

The only way to shut the machine down was to pull apart the mutiblock leading to the shut off solenoid

[jackpreacher]

?........The only way to shut the machine down was to pull apart the mutiblock leading to the shut off solenoid

.....it never even occurred to me to do that in that moment of pure adrenalin rush........


...and here's why:

A million years ago I locked myself out of an old Hillman Avenger that was still running (don't ask) but you could unlock the bonnet on those from the outside in those prehistoric times.........so, I grabbed hold of the distributor cap...............these modern day medical defribulators are nowt compared to the the power of a Hillman Avengers Hi-Tension DC.

[Muz]

Yes that would tickle

[Dan]

Brr -9 where I was yesterday at Aultguish ........ keep that heater lit